you have said, that you are clicking on the "spam button" - there i have the effect, that only the mail message is moved to the junk mail Folder!
Try to use the button Spam-Adress!
I have ca. 30 Mailaccounts in Outlook with sometimes the same spam. From all accounts the spam is recognized and moved with a success rate over 99%. (ca. 400 Spam-Mails per Day).
The only Problem i have is that if a spam mail is not recognized - only the marked mail is moved to spam. if i have on other accounts the same spam i have to move them manually with the spam-button. Here the "Spam-Adress" button is not working because u have already the Sender blacklisted.
Thorsten